chore: fix broken script for generating parser tests (#8945)

---------

Co-authored-by: gtmnayan <50981692+gtm-nayan@users.noreply.github.com>
Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>

packages/svelte/test/parser/update.js

@@ -2,8 +2,12 @@
 // equivalents. Only use it when you're sure that you haven't
 // broken anything!
 import * as fs from 'node:fs';
+import { dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
 import glob from 'tiny-glob/sync.js';
 
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
 glob('samples/*/_actual.json', { cwd: __dirname }).forEach((file) => {
 	const actual = fs.readFileSync(`${__dirname}/${file}`, 'utf-8');
 	fs.writeFileSync(`${__dirname}/${file.replace('_actual.json', 'output.json')}`, actual);